package com.gis.wc;

import org.apache.flink.api.common.functions.FlatMapFunction;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.operators.DataSource;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.util.Collector;

/**
 * @author LnnuUser
 * @create 2021-09-05-上午10:46
 */

// 批处理word count
public class WordCount {
    public static void main(String[] args) throws Exception {

        // 创建执行环境
        ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

        // 从文件中读取数据
        String inputPath = "/home/lnnu/IdeaProjects/FlinkTutorial/src/main/resources/hello.txt";

        DataSource<String> inputDataSet = env.readTextFile(inputPath);

        // 对数据集进行处理,按照空格分词展开，转换成（word，1）这样的二元组进行统计
        DataSet<Tuple2<String, Integer>> result = inputDataSet.flatMap(new MyFlatMapper())
                .groupBy(0)     // 按照第一个位置的word进行分组
                .sum(1);          // 将第二个位置上的数据求和

        result.print();
    }

    // 自定义类，实现FlatMapFunction接口
    public static class MyFlatMapper implements FlatMapFunction<String, Tuple2<String, Integer>> {

        @Override
        public void flatMap(String s, Collector<Tuple2<String, Integer>> collector) throws Exception {

            // 按照空格分词
            String[] words = s.split(" ");

            // 遍历words，包成二元组输出
            for (String word: words) {
                collector.collect(new Tuple2<>(word, 1));
            }
        }
    }
}
